The present invention relates to impact modifier compositions which enhance the impact strength performance properties and also lower the viscosity of melt processed plastics resins. In particular, the impact modifier compositions of the present invention improve the impact and viscosity properties of polyvinyl halide resin compounds such as polyvinyl chloride. The invention also provides methods of making these impact modifier compositions.
Plastics resins are used in numerous applications, for example, in plastics sheet, and in blow and extrusion moulded articles such as bottles and containers and building materials. However, articles moulded from resins often suffer from performance problems due to their rigid nature which causes the moulded articles to break or crack easily. To counteract these difficulties it is well known to mix the plastics resins with additive materials, for example, impact strength modifiers to improve the impact strength properties of the moulded articles.
Another important property which markedly influences the efficiency of moulding plastics resins is the viscosity of the resin at the moulding or processing temperature (hereafter xe2x80x98melt viscosityxe2x80x99). To ensure that the extrusion and blow moulding pressures are low so as to maximise the efficiency of the extrusion/moulding equipment, it is highly advantageous for the melt viscosity to be kept to a minimum, whilst at the same time ensuring that the shape of the moulded article is retained and that no sagging occurs.
Although impact modifiers improve impact strength, there is a further problem in that they cause the flowability of the resin to decrease, i.e., the melt viscosity of the resin increases. This problem is noted by R. D. Deanin et al in Polym. Material Sci. Eng. 75, 502, 1995. This journal article teaches that the viscosity problem can be overcome by the addition of small amounts, about 5 parts per hundred parts of resin, of solid plasticizers such as dicyclohexyl phthalate. However, although such plasticizers do reduce resin melt viscosity, they do so at the expense of increasing embrittlement or decreasing the impact strength of plastics resins.
There are also several patents which disclose the enhancement of impact strength performance of plastics resins using conventional impact modifiers in combination with various other additives. For example, U.S. Pat. No. 5,780,549 discloses that the impact resistance of PVC compounds is improved by first forming a modified impact modifier by allowing polybutene polymer to absorb into a conventional impact modifier and then adding this modified impact modifier to PVC and processing in the usual manner. U.S. Pat. No. 5,360,853 discloses blending together PVC, an impact modifier and polysiloxane to obtain a PVC resin with enhanced impact strength resistance as compared to PVC resin with the impact modifier alone. Similarly, U.S. Pat. No. 3,428,707 teaches increasing the impact strength of a PVC/impact modifier composition by preparing a blend of PVC and an impact modifier and then milling this blend with polysiloxane. Although these prior art documents disclose that impact strength is improved by the addition of polybutene and polysiloxane, these materials are expensive and this reduces the cost effectiveness of the plastics resin.
Canadian Patent Application No. 2,102,478 discloses that the impact strength of polyvinyl chloride resin may be improved by mixing it with an impact modifier and a lubricant system; the latter comprises a long chain carboxylic acid, a metal salt of a carboxylic acid and mineral oil. However, either the process used to combine the PVC and the other components in the reaction system together, or the choice of reaction components, or both, does not appear to give either a consistently large decrease in the viscosity or a consistently large increase in the impact strength of the melt processed PVC.
A journal article published by D. M. Detweiler et al in Society of Plastics Engineers Annual Technical Conference: Paper V 19, 647, (1973), discloses a study of the interaction of impact modifiers and lubricants. The experiments were conducted by mixing together a polyvinyl chloride resin, an impact modifier, a stabiliser and a lubricant. The results show that the addition of the lubricants can improve the performance of the MBS impact modifier but they apparently have very little effect on the melt viscosity of the PVC resin.
Finally, an article published in Polymer Science U.S.S.R. Vol. 22, No. 10 pp 2395-2402, 1980 by T. B. Zavarova et al teaches that the impact strength of a PVC plastic resin containing a methyl methacrylate/butadiene/styrene (MBS) impact modifier can be increased by the addition of a lubricant such as butyl stearate, glycerin monoricinoleate, transformer oil or xcex1-hydroxyisobutyric acid. However, this prior art teaches, in particular, that the presence of the butyl stearate has no effect on the melt viscosity of PVC-MBS compositions.
The aim of the present invention, therefore, is to provide an impact modifier composition which enhances the impact strength properties of melt processed plastics resins and which also has a lowering effect on the melt viscosity of such plastics resins.
Accordingly, in a first embodiment, the present invention provides an impact modifier composition comprising at least one impact modifier and at least one mineral oil, and further comprising 0-50% by weight of the composition of one or more plastics resins. Preferably the composition comprises 0-20% by weight of the composition of one or more plastics resins.
The invention also provides a method of producing the impact modifier composition described above, comprising mixing together:
a) at least one impact modifier;
b) at least one mineral oil; and
c) 0-50% by weight of the composition of one or more plastics resins.
The at least one impact modifier can be used (i) in latex or emulsion form, in which case the resulting impact modifier composition may be isolated by coagulation or spray drying; or (ii) in dry powder form.
The present invention also provides for the use of the impact modifier composition described above to improve the impact strength and to lower the viscosity of melt processed plastics resins.
Impact modified plastics resins may be prepared by combining one or more plastics resins with the impact modifier composition described above.
A second embodiment of the present invention provides a method of preparing an impact modified plastics resin comprising combining at least one mineral oil with at least one impact modifier and a plastics resin, wherein the at least one mineral oil is not added as, or as part of, an external lubricant for the plastics resin.
Preferably, the amount of impact modifier added to the plastics resin is from 0.1 to 20 parts per hundred parts of resin (PHR).
The invention also provides for the use of the method according to the second embodiment to produce an impact modified plastics resin having a reduced melt viscosity.
The present invention also includes articles that may be made from the impact modified plastics resins described above.
In all of the above embodiments, suitable plastics resins include polyvinyl halide resins, such as polyvinyl chloride; polyalkylene terephthalate polymers; such as polyethylene terephthalate and polybutyleneterephthalate polymers; polycarbonate polymers; polyalkylene terephthalate/polycarbonate polymer blends; acrylonitrile/butadiene/styrene polymers; polyolefin polymers, such as polyethylene, polypropylene; mixed polyolefin polymer blends such as polymer blends of polyethylene and polypropylene polymers; and polyketone polymers. The term xe2x80x9cplastics resinxe2x80x9d is to be interpreted to include mixtures or blends of one or more of these polymers. The term xe2x80x98polymerxe2x80x99 is to be interpreted to include all types of polymer molecules characterized as having repeating units of atoms or molecules linked to each other such as homopolymers co-polymers including block, random, and alternating co-polymers, grafted polymers, and co-polymers terpolymers, etc.
Also, in all of the above embodiments, it is preferable that the weight ratio (hereafter xe2x80x9cratioxe2x80x9d) of mineral oil to impact modifier is from 0.1:10 to 4:10. Further preferably, the ratio is 1.5:10. The actual ratio used will depend upon the relative solubility of the mineral oil in the particular plastics resin and the impact modifier. However, when the ratio is too large, for example 5:1, problems of over lubrication are encountered which makes milling difficult.
The mineral oils useful in the invention are preferably paraffinic oils with saturated straight or branched chains or rings containing at least 20 carbon atoms; naphthenic or relatively naphthenic, that is, containing saturated monocyclic (from 4 to 12 carbon atoms) or polycyclic (from 13 to 26 carbon atoms) hydrocarbon oils; microcrystalline wax, paraffin wax and low molecular weight polyolefins such as polyethylene wax, either in liquid, powder or flake form; aromatic oils with a minimum molecular weight of 300; also suitable are mineral oils known as white mineral oils which are a complex mixture of saturated paraffinic and naphthenic hydrocarbons and are free of aromatic compounds, sulphur containing compounds, acids and other impurities. Preferred mineral oils are those which are easy to handle and do not present environmental and/or health concerns, such as those which have a low viscosity and those with a low volatility at the temperatures used during the milling and extrusion blending processes. Particular preferred mineral oils include the heavy mineral oil such as those termed USP mineral oils which typically have a density of from 0.860-0.89 g/m and light mineral oils which typically have a density of from 0.80-0.87 g/m. The preferred heavy mineral has a density of 0.862 g/ml and the preferred light mineral oil has a density of 0.838 g/ml, both of these oils are available from the Aldrich Chemical Company.
Any impact modifier is contemplated for use in the present invention, especially preferred include graft copolymers comprising a rubbery polymeric core and one or more rigid shells. Examples of suitable impact modifiers include methyl methacrylate/butadiene/styrene based resins (MBS), acrylic based impact modifiers (AIMS), acrylonitrile/butadiene/styrene based graft copolymers (ABS), ethylene/vinyl acetate based graft copolymer (EVA), methylmethacrylate/acrylonitrile/butadiene/styrene based copolymers (MABS), butadiene/styrene based copolymers (BS), methacrylate/butadiene based copolymers (MB), methylmethacrylate/acrylate/acrylonitrile based copolymers (MAA), chloropolyethylene based copolymers (CPE); block copolymers based on styrene/butadiene/rubber (SBR) and styrene/ethylene/butene/styrene block copolymers (SEBS), ethylene/propylene/diene monomer (EPDM) and butyl acrylate based polymer modifiers modified with siloxane and/or butadiene monomers in the core. Preferred graft impact modifiers are methyl methacrylate/butadiene/styrene based graft copolymers and acrylic based impact modifiers.
It is contemplated that the at least one mineral oil is mixed with the impact modifier by either (i) combining the mineral oil directly or indirectly with impact modifier after the impact modifier has been formed or (ii) adding mineral oil at the start of, or at some point during, the reaction process used to prepare the impact modifier.
A general description of the preparation of impact modifiers is fully described in the prior art, for example, U.S. Pat. Nos. 2,802,809, 3,678,133, 3,251,904, 3,793,402 2,943,074, 3,671,610, and 3,899,547, which documents are incorporated herein by reference.
In the particular embodiment disclosed in U.S. Pat. No. 3,678,113, a composite interpolymer is disclosed which comprises a multi-phase acrylic base material comprising a first, elastomeric phase polymerized from a monomer mix, comprising at least about 50 weight percent of an alkyl acrylate having about two to eight carbon atoms in the alkyl group and a minor amount of a cross-linking agent, and a second, rigid thermoplastic phase polymerized from a monomer mix comprising at least about 50 weight percent alkyl methacrylate having one to four carbon atoms in the alkyl group, and having a molecular weight of from about 50,000 to 600,000.
The composite interpolymer material is ordinarily and preferably prepared by emulsion polymerization of the elastomer as a discrete phase from a monomer mix of at least about 50 weight percent of an alkyl acrylate and about 0.05 to 5.0, preferably 0.1 to 3.5, weight percent of a cross-linking agent. Upon completion of the polymerization of the elastomeric phase, i.e., substantial exhaustion of the monomers in the initial polymerization mix, the rigid thermoplastic phase is then formed by polymerization in the presence of the elastomer, in the same emulsion, and preferably with minimal penetration or swelling of the elastomer phase, from a monomer mix comprising at least about 50 weight percent C1 to C4 alkyl methacrylate. The polymerization of the rigid thermoplastic phase of the composite is preferably conducted in such a fashion that substantially all of the rigid phase material is formed on or near the surface of the elastomeric phase as hereinafter more fully described, and without the formation of substantial numbers of new particles in the emulsion.
The acrylic elastomer phase of the composite interpolymers of the present invention comprises at least 50 percent of alkyl acrylate units. The alkyl esters of acrylic acid having alkyl groups of two to eight carbon atoms, and preferably four carbon atoms, are contemplated. Longer chain alkyl groups can be used, although substantial difficulties in the polymerization can result, and such monomers are not preferred inclusions.
Other acrylic monomer, including acrylonitrile, methacrylonitrile, alkylthioalkyl acrylates such as ethylthioethyl acrylate, and the like, alkoxyalkyl such as methoxyethyl acrylate, and the like, also can be used in proportions ranging up to about 49.95 weight percent. Interpolymers of these acrylates can further include up to about 20 weight percent of other non-acrylic copolymerizable monomers, such as styrene, alkyl methacrylates, olefins, vinyl ethers, amides and esters, vinyl and vinylidene halides, and the like.
Another inclusion in the acrylic elastomer includes polyfunctional monomers capable of forming a cross-linked elastomer, such as polyethylenically unsaturated monomers like polyacrylates and polymethacrylates, divinyl benzene, and monomers capable of ionic and coordinate cross-linking such as acid groups and organic and inorganic bases and other electron donating groups coordinating with suitable electorophilic agents. The resulting cross-linked elastomers are referred to as gelled polymers to describe that physical characteristic of the polymers. The polyethylenicauly unsaturated monomers include polyacrylic and polymethacrylic esters of polyols, such as 1,3-butylene diacrylate and dimethacrylate, trimethylol propane trimethacrylate and the like, di-and tri-vinyl benzene, vinyl acrylate and methacrylate, and other common cross-linking monomers. These cross-linking monomers can be generally characterized, for purposes of the present invention, as compounds having at least two polymerizable ethylenically unsaturated reactive groups which are non-conjugated or, if conjugated, mediately conjugated. Mediate conjugation results when the reactive groups are conjugated with and/or through an intermediate, non-polymerizable unsaturated group. For example, the two vinyl groups of divinyl benzene are not conjugated with each other except by virtue of the xe2x80x9cmediatingxe2x80x9d effect of the aromatic unsaturation. Likewise, the polymerizable unsaturation of vinyl acrylate is conjugated only through the mediation of the carbonyl unsaturation. The polymerizable groups of butadiene, on the contrary, are directly conjugated, and is accordingly not within the scope of the presently, contemplating cross-linking monomers. Use of directly conjugated materials such as butadiene and the like results in failure to attain the benefits of the present invention.
Preferred elastomers within the scope of the present invention include acrylic interpolymers prepared from monomer mixtures comprising about 50 to 99.95 parts by weight alkyl acrylate monomers, wherein the alkyl group contains one to eight carbon atoms, about 5 to 30 parts by weight other acrylic monomers, about 0 to 20 parts by weight of other non-acrylic ethylenically unsaturated monomers and about 0.05 to 5, preferably 0.1 to 3.5 parts by weight of a polyunsaturated non-conjugated or mediately conjugated cross-linking monomer.
In the preparation of the elastomeric phase, it will ordinarily be preferred to choose monomer systems and proportions so as to effect control the glass transition temperature, (Tg), of the phase. The Tg of the elastomeric phase should be, in most situations, below about 10xc2x0 C., and preferably below about 0xc2x0 C. In most preferred formulations, Tg should be below about xe2x88x9230xc2x0 C.
The rigid thermoplastic phase of the composite interpolymer of the present invention includes the acrylic thermoplastics polymerized from monomer mixtures comprising 40 to 100 weight percent alkyl methacrylate, wherein the, alkyl group has one to four carbon atoms, one or more acrylic comonomers in quantities of 0 to 60 weight percent such as other alkyl and aryl methacrylates, alkyl and aryl acrylamides, substituted alkyl and aryl acrylic and methacrylic monomers, wherein the substitutents can be halogen, alkoxy, alkylthio, cyanoalkyl, amino, alkylthio, and other like substituents, 0 to 60 weight percent non-acrylic unsaturated monomers which impart rigid character to the rigid phase, such as vinyl aromatics, preferably styrene and .alpha.-methylstyrene, vinyl and vinylidene halides, and vinyl-substituted nitriles, and 0 to 10 weight percent of still other nonacrylic unsaturated monomers, including vinyl esters, vinyl ethers, vinyl amides, vinyl ketones, olefins, and the like. To obtain higher service temperatures, cycloalkyl esters of methacrylate acid are useful wherein the cyclic portion contains five, six, or seven carbon atoms, with or without an additional alkyl bridge, the alkyl portion of the cycloalkyl group containing up to 10 carbon atoms, such as isobornyl methacrylate.
The rigid phase is further characterized by molecular weight ranging from about 50,000 to 600,000, preferably 50,000 to 500,000, and still more preferably 50,000 to 300,000. A particularly effective molecular weight for attaining the full benefits of the present invention is about 100,000 to 250,000, which level is also relatively convenient to attain in preparing the composite interpolymers of the present invention. Unless otherwise noted the term xe2x80x9cmolecular weightxe2x80x9d refers to viscosity average molecular weight (Mv).
In the preparation of the rigid thermoplastic phase, it will often be desirable to obtain a glass transition temperature, (Tg), above at least about 20xc2x0 C., and preferably above about 50xc2x0 C. In most preferred formulations, Tg of the rigid phase should be above about 90xc2x0 C.
The composite acrylic interpolymers of the present invention are prepared in suspension or emulsion polymerization procedures utilizing a multi-stage or sequential technique. In simplest form, the elastomeric phase is formed in an initial stage and the rigid thermoplastic phase is formed in a second stage. Either the elastomeric or rigid phases can themselves also be sequentially polymerized. The monomers of the initial stage, together with polymerization initiators, soap or emulsifiers, polymerization modifiers and chain transfer agents and the like are formed into the initial polymerization mix and polymerized, e.g. by heating and mixing the emulsion, in well known and wholly conventional fashion, until the monomers are substantially depleted and a seed polymer is formed. Monomers of the second, and in turn, of each additional stage are then added with appropriate other materials e.g. supplementary initiators, soap, modifiers, and the like, so that the desired polymerization of each stage occurs in sequence to substantial exhaustion of the monomers. In each stage subsequent to the first, the amounts of the initiator and soap, if any, are maintained at a level such the polymerization occurs at or near the surface of the existing particles, and no substantial number of new particles, or seeds, form in the emulsion. When the two phases of the composite interpolymer are either themselves formed by sequential polymerization, the monomer constituents of the various stages of each phase may vary from stage to stage, or all the components can be present throughout the entire phase polymerization. The stages can vary in hardness, from a very soft elastomer first stage seed to the hardest rigid thermoplastic. Both the elastomer and rigid thermoplastic can contain chain transfer agents, in one or all stages, and any or all stages of the composite can contain polyfunctional cross-linking monomers. The molecular weight of the hard phase might be controlled by modification of either the hard phase itself with chain transfer agents or it might be controlled by providing sites on the elastomer particles that act as chain transfer agents in the hard phase. These techniques include any type of chain transfer agents in the elastomeric phase and specifically include pendant mercaptan groups and di-functional monomers such as polyunsaturated monomers which by the difference in the reactivity between the functional groups cause functional groups such as unsaturation to remain in the elastomer which will act as claim transfer agents in the latter hard phase.
The polymerization reactions can be initiated by either thermal or redox type initiator systems. Examples of thermal initiators include the organic peroxides, such as benzoyl peroxide, substituted benzoyl peroxides, acetyl peroxides, lauroyl peroxide, t-butyl hydroperoxide, di-t-butyl hydroperoxide, peresters, such as t-butyl peroxypivilate, axo-type initiators such as azo-bis-isobutyronitrile, persulfates, such as sodium, potassium or ammonium persulfate, and peroxyphosphates such as sodium, potassium, or ammonium peroxyphosphate. Redox initiators are generally a combination of a hydroperoxide, such as hydrogen peroxide, t-butyl-hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, and the like, with a reducing agent, such as a sodium, potassium, or ammonium bisulfite, metabisulfite, or hydrosulfite, sulfur dioxide, hydrazine, ferrous salts, ascorbic acid, sodium formaldehyde sulfoxylate and the like, as are well known in the art. In the utilization of emulsion polymerization techniques, it is preferred that a oil soluble initiator system be utilized in preference to water soluble initiator systems.
Examples of emulsifiers or soaps suited to polymerization processes of the present invention include alkali metal and ammonium salts of alkyl, aryl, alkaryl, and aralkyl sulfonates, sulfates and polyether sulfates, ethoxylated fatty acids, esters, alcohols, amines, amides, alkyl phenols, complex organophosphoric acids and their alkali metal and ammonium salts.
Chain transfer agents are ordinarily desirable in the polymerization mix for the control of the molecular weight of the rigid thermoplastic phase. The art is well aware of numerous techniques for the control of molecular weight, and there is no criticality in the present invention in any particular technique. A preferred technique, however, is the inclusion of a lower alkyl mercaptan, such as sec-butyl mercaptan, in the polymerization mix during the stage or stages when the rigid phase is polymerized. It has been noted that higher normal alkyl mercaptans, i.e., C10 to C12 are not effective in reasonable amounts and should ordinarily not be used. In particular, it was noted that n-dodecyl mercaptan was ineffective for attaining the molecular weight range required in the present invention without substantial contamination of the product with residual mercaptan. Other techniques for controlling molecular weight of the rigid phase include the presence of relatively large amounts of peroxide and operations at high temperature, and the presence of allyl compounds.
The composite interpolymer of the present invention is comprised of the two discrete phases. Because of the extreme complexity of the interrelations among the various ingredients, it is difficult to isolate and describe the physical characteristics of the component phases. Because of the degree of cross-linking in the elastomer phase no adequate or meaningful determination of molecular weight can be ascertained for the elastomeric phase. Extraction of the composite interpolymer permits determination of the rigid phase, which will have a measurable molecular weight of from about 50,000 up to as much as 600, 000. The elastomer portion has been ascertained to have a swelling ratio (weight of wet, acetone extracted, insoluble gel/weight of dry, acetone extracted gel) ranging from about 2 to 12.
The relative proportions of the elastomeric and harder thermoplastic phases can vary considerably, but will ordinarily be in the range of about 40-90 weight percent elastomer and conversely about 20-60 weight percent thermoplastic, preferably on the order of about 50-80 weight percent elastomer and about 20-50 weight percent rigid thermoplastic.
It is preferred that the polymerization conditions be maintained such that the rigid phase is polymerized at or near the surface of the elastomer phase, and preferably in a discrete layer which encapsulates the elastomer and with minimized penetration and swelling of the elastomer of the rigid phase monomers. The encapsulation is not narrowly important, however, and often entirely satisfactory results are attained when the rigid phase covers only a portion of the surface of the elastomer, but it has been noted that when too large a proportion of the volume of the elastomer is penetrated and swelled by the rigid phase monomers, the impact properties and processing characteristics of the blends of the composite interpolymer with the vinyl halide polymers are detrimentally affected.
By control of the polymerization variables, it is possible to control the particle size of this composite interpolymer, in a fashion well-known to the art. The particle size is not of narrow significance to the present invention; it can range from as low as about 500 angstroms, or even less, up to as large as about 3,000 angstroms or even more. In certain circumstances, however, more narrow particle size ranges can be of significance. For example, it is preferable to utilize particles as large as possible, consistent with the effective and economical preparation of the material. In the manufacture of composites for the preparation of extruded shapes, it is accordingly preferred that the particle diameters range from about 1,500 to 2,500 angstroms, more preferably 1,600 to 2,300 angstroms. See, for example, Column 2, line 10 through Column 5, line 58 of U.S. Pat. No. 3,678,133. A typical process for making an impact modifier involves the steps of: a) mixing together one or more first monomers an initiator and, optionally, an aqueous surfactant solution; b) heating the resulting mixture to polymerise the monomers; optionally c) combining the resulting polymerised product from step b) with one or more second monomers, a further initiator and further surfactant and heating the resulting mixture to produce an impact modified latex; and d) isolating the resultant impact modifier. This process can be an emulsion, a mini-emulsion or a micro-emulsion polymerisation process, a suspension polymerisation process, a dispersion polymerisation process, a precipitation polymerisation process or an inverse emulsion polymerisation process. 
The MBS resins of the invention can be obtained, in general, by emulsion-polymerization of butadiene or a monomer mixture of butadiene as the principal constituent and styrene, with addition of a small quantity of a cross-linking agent, to produce a polymer latex, causing a monomer mixture containing styrene and methyl methacrylate and a small quantity of a cross-linking agent as an additive to be adsorbed on the polymer latex and be polymerized thereon, or further adding thereto methyl methacrylate containing a cross-linking agent, and causing polymerization, and subjecting the latex thus obtained to salting out, whereby MBS resin in the form of fine particles can be obtained.
The present invention, therefore, provides a process for combining at least one mineral oil with at least one impact modifier comprising forming the at least one impact modifier using the steps of:- a) mixing together an aqueous surfactant solution, a first monomer material and an initiator; b) heating the resulting mixture to polymerise the monomers; optionally c) combining the resulting polymerised product from step b) with a second monomer, a further initiator and further surfactant and heating the resulting mixture to produce a core/shell latex; and d) isolating the resultant impact modifier; wherein at least one mineral oil to the reaction mixture formed during any one or more of the steps a), b), c) or d).
The above process is also useful to combine impact modifiers with oils which are not mineral oils. These oils include polymers which have a weight average molecular weight (Mw) of 5000 or less comprising polybutene, polydimethylsiloxane, polypropylene, polybutadiene, polyisoprene, preferably the polybutene has a Mw of 300-1500 and the polydimethylsiloxane has a Mw of 900-3100; alkylacrylates having an alkyl group containing 12 or more carbon atoms such as stearyl(meth)acrylate, lauryl(meth)acrylate; esters containing carboxylic acids or alcohols with 12 or more carbon atoms, for example, methyl stearate, ethyl stearate, butyl stearate, stearyl citrate; vegetable oils such as sunflower oil, peanut oil or olive oil; marine oils such as cod liver oil; industrial oils like, castor oil and linseed oil; palm oil such as coconut oil and animal fats such as tallow.
The impact modifier composition of the present invention may also comprise additives such as stabilisers, internal lubricants such as calcium stearate, pigments e.g. TiO2, and processing aids such as PARALOID K-120N(trademark) (available from Rohm and Haas Company).